Prime Number programs with Python 3

Finnaly I finished the program after almost 5 hours of work in two days.
Here the program

def prime_num(num):
    if num == 2:
        print('%s is a prime number' % num)
    elif num < 2:
        print('%s is not a prime number' % num)
    else:
        for i in range(2, num):
            if num % i == 0:
                print('%s is not a prime number' % num)
                break        else:
            print('%s is a prime number' % num)

prime_num(16)